1. Field of the Invention
This invention relates generally to concrete product making machinery and more particularly to a method and apparatus for high speed manufacturing of a wide variety of high quality products.
2. Description of the Prior Art
Prior art machines for forming concrete products within a mold box and include a product forming section comprising a stationary frame, an upper compression beam and a lower stripper beam. The mold box includes a head assembly that is mounted on the compression beam, and a mold assembly that is mounted on the frame and receives concrete material from a feed drawer. An example of such a system is shown in U.S. Pat. No. 5,807,591 which describes an improved concrete products forming machine (CPM) assigned in common to the assignee of the present application and herein incorporated by reference for all purposes.
In use, the feed drawer moves concrete material over the top of the mold assembly and dispenses the material into the contoured cavities of the mold assembly. The feed drawer typically includes an agitator assembly within the drawer that operated to break up the concrete and improve its consistency prior to dropping it into the mold. As the concrete material is dispensed, a vibration system shakes the mold assembly to spread the concrete material evenly within the mold assembly cavities in order to produce a more homogeneous concrete product. A wiper assembly, mounted to the front of the feed drawer, acts to scrape excess concrete from the shoes when the feed drawer is moved to an operative position above the mold assembly.
After the concrete is dispensed into the mold cavities, the feed drawer retracts from over the top of the mold assembly. A spreader, bolted separately to the front of the feed drawer, scrapes off excess concrete from the top of the mold when the feed drawer is retracted after filling the mold cavities. The compression beam then lowers, pushing shoes from the head assembly into corresponding cavities in the mold assembly. The shoes compress the concrete material during the vibration process. After compression is complete, the stripper beam lowers as the head assembly pushes further into the cavities against the molded material. A molded concrete product thereby emerges from the bottom of the mold assembly onto a pallet and is conveyed away for curing and a new pallet moved in its place beneath the underside of the mold assembly.
Several drawbacks have been identified with these prior concrete products forming machines. First, it has traditionally been quite time consuming to change mold and corresponding shoe assemblies so that new product configurations can be produced in the machine. Accordingly, manufacturing efficiency is reduced. Second, prior art vibration systems are known to impart slightly horizontal vibrational forces which cause the shoes to impact against the interior of the mold cavities when inserted. This results in increased wear on these parts with early and costly replacement necessary. Third, the process of moving of concrete material from the feed box to the mold cavities is a fairly messy procedure. Again, efficiency and product quality is reduced due to the requirement of frequent clean-ups.
Finally, prior art concrete products forming machines have traditionally been produced using hydraulic power systems which are noisy, energy inefficient, requires high maintenance, are messy, and are unwieldy with hoses and tubes routed through and around the machine.
Accordingly, there is a need for a high output concrete product forming machine that efficiently adapts to making a wide variety of high quality products, is energy efficient, avoids oil leakage exposure and contamination, requires minimal maintenance, and is easily serviced.